how to sweat a threaded valve?

I have a valve w/ threads on the inlet and outlets. Is it preferable to sweat the copper pipe by inserting it inside the in/outlet or use a female adapter and sweat the pipe to it. The attached picture shows both options.

I believe before sweating we need to remove the cartridge which is usually made of plastic and can melt during sweating. But on this valve, I can see a yellow plastic tip sticking out, but I don't see any way to disassemble the valve. It's a diverter valve (Kenzo from Pfister).

How can I insert this valve between my shower head and shower supply valve without damaging it.

FWIW, it's always a good idea to take the cartridge out and flush the lines before reinstalling it. So, if you have to take it apart anyway, why use the adapters which adds another joint that could leak? Adds cost, too (not much, but hey, it's still money).

I have not claim on being a pro, and as HJ points out, most of us DIY types solder to the adapter then screw the assembly into the valve. Why? What did you not understand about me not being a pro? LOL Yes, Jim, it does cost a few cents to do that, but I'll spend a few cent on insurance to potentially save dollars on replacing a valve that got too hot. I'd like to think that I have good enough soldering skills to not screw up, but I'm not willing to gamble to find out.

You missed my point...many installation instructions tell you to remove the cartridge, turn the water on to flush the lines out (prevents clogging up the new cartridge), then reinstall it. So, if you follow instructions, you'd have the cartridge out so why not solder the pipes in then - it's more robust and less prone to problems.

Thanks for your input all. In my case, if I use an adapter I might have to screw it to the valve first, then sweat the copper pipe to the adapter.
The reason is the supply valve is already in place and I don't need to move it. Since I can't rotate it, I need to screw the adapter first than slide the pipe in and sweat it.

Note a great idea...neither the tape nor pipe dope really like the heat of soldering right next to it. Then, once you've got the pipe solid with the soldered connection, if the threaded one does leak, you have to unsolder things and probably cut thing in order to be able to pull it out and fix things.

I didn't thought about that tape, but that is a good catch. Thanks.
I see no advantage of using the adapter at this point. More joins is more potential points of failure.
If I could assemble the whole system on the floor and then attach it to the wall, I can see how the adapter could make it easier..
But I don't want to disconnect the supply valve from the PEX tubes and have to reattach it later.